Can't expand node from code

Following the Vaadin book I created a tree for my application with the exception that I add Property items instead of strings to wrap some objects I’m putting in the tree. When I try to expand the root node I get a false value. Looking at the tree code that should be because areChildrenAllowed(itemId) is returning false. I’m trying to figure out how to set that to true. Any ideas?

XincoCoreNodeProperty rootProperty = new XincoCoreNodeProperty(xcns);
        //Clear tree and start over
        root = xincoTree.addItem(rootProperty);
       //This adds children from database
        //Expand root

Here’s the code of the property:

package com.bluecubs.xinco.core.server.vaadin;

import com.bluecubs.xinco.core.server.service.XincoCoreNode;

 * @author Javier A. Ortiz Bultrón <>
public class XincoCoreNodeProperty implements Property {

    private XincoCoreNode node = null;

    public XincoCoreNodeProperty(XincoCoreNode node) {
        this.node = node;

    public String toString() {
        return node == null ? "Empty" : node.getDesignation();

    public Object getValue() {
        return node;

    public void setValue(Object newValue) throws ReadOnlyException, ConversionException {
        if (newValue instanceof XincoCoreNode) {
            if (isReadOnly()) {
                throw new ReadOnlyException();
            node = (XincoCoreNode) newValue;
        } else {
            // Don't know how to convert any other types
            throw new ConversionException();

    public Class<?> getType() {
        return XincoCoreNode.class;

    public boolean isReadOnly() {
        return true;

    public void setReadOnly(boolean newStatus) {
        throw new UnsupportedOperationException("Not supported yet.");

I’m guessing I need to access the Hierarchical container somehow. Any ideas?